10 Head-Scratching Facts About Gray Hair

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Whether it’s no big deal or a perplexing affront to your vanity, gray hair is a fact of life—and still a bit of a mystery.

1. How Hair Turns Gray

Hair grows in a follicle, a bulb-like tube on your scalp. The average head has 100,000 to 150,000 follicles, each operating independently from the others. Hair in its basic, unpigmented state is white. It gets its color from melanin, a pigment that also determines skin color. Two types of melanin, eumelanin (dark brown or black) and phaeomelanin (reddish yellow), combine to make all the hair colors. One hypothesis for why hair goes gray is that aging slows or stops the hair from accessing the melanin, so it comes out gray, silver, or white instead.

2. Hair May Bleach Itself From The Inside Out

New research reveals that graying may be from a build-up of hydrogen peroxide in the hair cell, which causes the hair to bleach itself on the inside. Cells naturally have a small amount of hydrogen peroxide in them, but it’s kept in check by an enzyme called catalase, which converts the hydrogen peroxide to oxygen and water. As we age, the body produces less catalase, so the hydrogen peroxide builds up and, according to the New York Times, blocks “the normal synthesis of melanin, the natural pigment in hair.” Thus the hair turns gray, giving new meaning to the phrase “peroxide blonde.”

3. Graying Is Caused By Heredity

When you’re born, your genes are already hardwired for when and how your hair will turn gray. This includes premature graying—people who gray before age 30 usually do so because it runs in the family. For most of us, graying starts in middle age. Dermatologists go by the 50/50/50 rule of thumb: by age 50, half the population will have at least 50 percent gray hair—although a worldwide survey showed that number was much lower, with only 6 to 23 percent of people half gray by age 50.

4. Race Is Also A Factor

In a related matter, race also determines when you’re likely to gray. In general, Caucasians gray in their mid-30s, Asians in their late-30s, and African Americans in their 40s.

5. Plucking One Gray Hair Will Not Cause Three To Grow In Its Place

This old wives’ tale is a myth. Each follicle can contain only one hair, and plucking it won’t make it able to produce multiple hairs. Furthermore, what you do to one follicle has no effect on the ones around it. That said, excessive plucking isn’t a good idea—it can damage the follicles and even stop hair production in that area altogether.

6. Stress Probably Plays A Role In Graying

When President Obama went gray his first term in office, was it stress, age, or a combination of both? Scientists aren’t sure. While some researchers say that your genes alone are responsible for gray hair, others say that there seems to be a connection between graying and stress, just no direct link to prove it. In 2011, a study by Nobel Prize winner Robert Lefkowitz discovered that long-term productions of the body’s fight or flight response—the instinctive ability to mobilize energy in response to a threatening situation—can damage your DNA and cause premature aging, including graying hair.

7. Trauma Won’t Make You Go Gray Overnight

Another myth is that a major shock will cause your hair to suddenly turn gray. This is sometimes called the Marie Antoinette Syndrome because the French queen’s hair supposedly turned white the night before she was beheaded. But hair, once grown, doesn’t change color, so waking up with a head of white hair isn’t going to happen. Although there is a very rare condition where all of the colored hairs can fall out, leaving only white hairs behind, the simpler answer is that Marie Antoinette probably just took off her wig.

8. Smoking May Cause You To Prematurely Gray

Multiple studies have linked smoking with premature aging, which includes early graying. In 2013, a study found that there is a significant relationship between smoking and gray hair in people under 30. In fact, “smokers were two and half times more prone to develop PHG” or premature hair graying.

9. Body Hair Also Turns Gray

All your body hair—chest, nose, pubic, etc.—can turn gray. Body hair tends to gray at a different rate than the hair on your head, which is why some men can have gray beards and brown hair, or visa versa. By the way, dyeing gray pubic hair is a thing. 

10. Someday, Research May Lead To A Gray Hair Cure

Scientists in Europe discovered a breakthrough with vitiligo, a disease where skin loses pigment and develops white patches. Like hair, vitiligo is caused by “massive oxidative stress via accumulation of hydrogen peroxide,” causing the skin to bleach itself from the inside out. Researchers have successfully treated the discolored skin and eyelashes of vitiligo patients, which has led some to predict a potential cure for gray hair. But while the idea sounds promising, history is full of tonics and creams claiming to cure gray hair. As far as we know, none of them have worked yet.

Science Finds a Better Way to Calculate 'Dog Years'

thegoodphoto/iStock via Getty Images
thegoodphoto/iStock via Getty Images

Anyone who has ever owned a pet is likely familiar with the concept of “dog years,” which suggests that one year for a dog is like seven years for a human. Using this conversion metric, a 2-year-old dog is akin to a high school freshman, while a 10-year-old dog is ready for an assisted living facility.

If that seems rather arbitrary, that’s because it is. But now, researchers at the University of California, San Diego have come to a more data-based measurement on dog aging through DNA.

The paper, published on the preprint server bioRxiv, based the finding on DNA methylation, a process in which molecules called methyl groups attach themselves to DNA and serve as an indicator of aging. Generally speaking, the older living beings get, the faster the rate of methylation. In the study, 104 Labrador retrievers were examined, with subjects ranging from 1 month to 16 years old. The results of their DNA methylation were compared to human profiles. While the rate of methylation tracked closely between the two—young and old dogs had similar rates to young and old people—adolescent and mature dogs experienced more accelerated aging.

Their recommended formula for comparing dog and human aging? Multiply the natural logarithm of a dog’s age by 16, then add 31. Or, just use this calculator. Users will see that a 2-year-old dog, for example, wouldn’t be the canine equivalent of a 14-year-old. It would be equivalent to 42 human years old and should probably start putting money into a 401(k). But because methylation slows considerably in mid-life, a 5-year-old dog is approximately a 57-year-old human, while a 6-year-old dog is nearing 60 in human years—a minor difference. Things level out as the dog gets much older, with a 10-year-old dog nearing a 70-year-old human.

Different breeds age at different rates, so the formula might not necessarily apply to other dog breeds—only Labs were studied. The work is awaiting peer review, but it does offer a promising glimpse into how our furry companions grow older.

[h/t Live Science]

Sssspectacular: Tree Snakes in Australia Can Actually Jump

sirichai_raksue/iStock via Getty Images
sirichai_raksue/iStock via Getty Images

Ophidiophobia, or fear of snakes, is common among humans. We avoid snakes in the wild, have nightmares about snakes at night, and recoil at snakes on television. We might even be born with the aversion. When researchers showed babies photos of snakes and spiders, their tiny pupils dilated, indicating an arousal response to these ancestral threats.

If you really want to scare a baby, show them footage of an Australian tree snake. Thanks to researchers at Virginia Tech, we now know these non-venomous snakes of the genus Dendrelaphis can become airborne, propelling themselves around treetops like sentient Silly String.

That’s Dendrelaphis pictus, which was caught zipping through the air in 2010. After looking at footage previously filmed by her advisor Jake Socha, Virginia Tech Ph.D. candidate Michelle Graham headed for Australia and built a kind of American Ninja Warrior course for snakes out of PVC piping and tree branches. Graham observed that the snakes tend to spot their landing target, then spring upward. The momentum gets them across gaps that would otherwise not be practical to cross.

Graham next plans to investigate why snakes feel compelled to jump. They might feel a need to escape, or continue moving, or do it because they can. Two scientific papers due in 2020 could provide answers.

Dendrelaphis isn’t the only kind of snake with propulsive capabilities. The Chrysopelea genus includes five species found in Southeast Asia and China, among other places, that can glide through the air.

[h/t National Geographic]

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